Fabrication and Localized Surface Plasmon Properties of Triangular Gold Nanowell Arrays in a Glass Substrate

Nanowell structure has been attractive in plasmonics, surface enhanced Raman scattering, nanocrystal synthesis, and biomolecular immobilization. Conventional nanowell structures have been carved into continuous thin metal films. This letter focuses on the fabrication and characterization of triangular gold nanowell arrays embedded in a back-filled non-metallic and transparent substrate. The nanowell dimensions can be controlled to produce an optically tunable localized surface plasmon resonance (LSPR) as a plasmonic sensor. AFM and LSPR spectroscopy confirm that the triangular Au nanowell structures are partially embedded in the surface of a transparent glass substrate to protect the shape and sharp features of the nanowell. Experimental spectral results and numerical calculations show that the extinction maximum of the LSPR is located in the NIR range, and correlates linearly with the base thickness of the nanowell. Numerical calculations to analyze the extinction spectrum of gold nanowell show that scattering of the nanostructure is dominant to compare to its absorption. LSPR-tunable nanowells can potentially be used for plasmonic sensors and biomolecular docking system platforms.